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Name:___________________________________________
For each of the below questions, write a short sentence or two to express (in your own words) your
answer. Keep the answers short, but use complete, correct, English sentences.
If it helps to clarify the questions, feel free to mentally prefix all the questions with the phrase
"According to the video…"
1. After you’ve watched all the videos, please answer this question:
Of all the videos that you watched, if you could pick one video to be re-recorded by the
instructor outside of class which would you choose? Why?
(Keep in mind the recording outside of class will omit any pauses from the instructor answering
student questions, have less hemming and hawing, etc, and generally be more concise)
< Write your answer here >
VIDEO: OOP Basics
2.
The basic idea behind object oriented programming is to combine what two things together, in
one place?
3. What is the first “part” of the rectangle class?
4.
Data should always be declared as what?
(Remember that you can always create a public method to access these data fields later.)
5. Even though the behavior (the methods) are defined for all instances of this class, calling the
calculateArea method will cause the area to be calculated based on what?
6.
What is the “constructor” used for?
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7. How does the constructor copy a starting value for the width (or height) into the rectangle’s
“permanent” memory?
8.
Given a choice between making a variable a permanent (“instance”) variable or a temporary
variable (typically a local variable), which type should you prefer to use? Under what
circumstances would you use the other one?
VIDEO: OOP Encapsulation
9. In C# you can use either a getHeight() method or a C# property. Why will we be using the
getHeight() method in this course?
10. In addition to allowing us to make basic changes to objects (such as changing r1’s height to be
10), what else does the accessor method make it easy for us to do?
(Hint: What if we try to change r1’s height to be -10)
11. If one makes the height field public what implications will that have for the program (in terms of
who can access that field)?
12. Is the public/private/protected feature that we’re looking at a security mechanism?
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13. Why are the constructor and calculateArea methods allowed to access the private height field?
14. Can the main method access the private height field of the r1 object?
15. Why is it ok to call the calculateArea method outside the Rectangle class (say, in main)?
16. Let’s say that you wanted to ensure that the height field of all rectangle objects are not
negative. Prior to the public/private/protected access-control mechanism, what was your only
option for ensuring that this would be true? Why would this be difficult?
17. Fill in the blank: “Just to recap, encapsulation is:________________________”
VIDEO: Object Oriented Programming (OOP): Background / Motivation
18. Prior to object oriented programming, how were programs (typically) divided up?
< Etc. >
19. How does object oriented programming (typically) change the way programs are divided up?
20. Fill in the blanks: “The basic idea is that in object oriented programming we’ll have a [Car] class,
which describes ______________, and we’ll have an individual object which describes
______________”
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21. Fill in the blank: “An object is _________________” ( about 6:30)
VIDEO: OOP: (Instance) Methods, Object Allocation Demo
22. What is a good type of name for a class (and what are a couple of examples of bad names for a
class)?
23. If you wanted to add a “Print” command to a class named Car, where would you put the Print
method’s definition? Describe the location in English, then copy the example code from the
video (at about the 1:50 mark)
(After 2:15 the video answers a number of tangential questions –skim this if you’re interested, but don’t
worry about recalling the details of this part of the video)
VIDEO: OOP: Instance Variables
24. Fill in the blank: “Unless you’ve got a really good reason [to do otherwise], you should always
make all your instance variables _____________”
25. When you create a new Car object, what value will be put into all of the instance variables for
that particular object?
26. Describe in your own words how the SetMaxSpeed method allows one to change the maximum
speed for a car object.
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27. Why is it ok to set maxSpeed in the SetMaxSpeed method, and then use it in the Print method?
28. How does writing out as your variable as this.maxSpeed help to make your program more
clear?
(Starting at about 9:30 there’s a very visual explanation of how memory is managed when creating and
using objects. Even though there aren’t a ton of questions about this, definitely watch this in order to
develop an intuition about how object creation & usage works!!)
29. What is the purpose of the invisible parameter named this? What information does it pass from
main to the SetMaxSpeed method?
30. Inside the SetMaxSpeed method, how does C# figure out what the (variable) name maxSpeed
refers to?
31. Because of the procedure you outlined in your answer to the prior question, is it possible to
create a local variable that has the same name as an instance variable?
32. Should you ever create a local variable that has the same name as an instance variable?
( Hint: NO!!!!!!!!!!!!!!  )
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33. Does the method’s name cause the action/effect of the method?
If not, why is it still a good idea to choose method names that describe the each method does?
34. The “Stack” is very, very efficient at doing what?
VIDEO: OOP: Access control (public/private), getter/setter methods
35. The primary purpose of access control is prevent my co-workers from doing what?
36. What can the SetMaxSpeed method do that will help prevent errors for being made in the
overall program?
37. What does the keyword “private” mean / what does it do?
38. If you try to access a private data member (say, in main), what error message will you get?
39. Why is main allowed to call SetMaxSpeed? Why is SetMaxSpeed allowed to change maxSpeed?
40. Another advantage to forcing everyone to use accessor methods is that you can change what
part of the class/program and yet NOT have to change the rest of the program?
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(Around the 9 minute mark there’s a blurb about exception handling – it is interesting to know about,
but you’re not required to know it (unless there’s other material in this class that specifically requires
you to know it) ).
41. Does access control protect you from intentionally malevolent actions by your co-workers? If
not, then where is it useful?
VIDEO: Overloading
42. Are overloading a method and overriding a method the same thing? If not, give a really quick,
intuitive explanation of each one (you haven’t seen overriding yet so don’t worry about
providing a detailed/entirely correct explanation – the main thing is that you know these are
different)
43. There’s an example of overloading in the video involving a printBox method (right around the 3
minute mark) – briefly summarize what we were trying to accomplish with the printBox
methods, and why it’s useful to have multiple methods that all have the same name.
44. The basic rule for figuring out if you’ve legally overloaded a method is if you’ve got enough
information at what point in the program? What information do you need, specifically?
45. Fill in the blank: “Overloading makes sense when you have one ___________, but a whole
bunch of different ____________”
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46. Can C# differentiate which version of the method to call based on the return value?
If not, why not?
47. Is it less efficient to call one overloaded version of the function, and then have it immediately
call the ‘real’ version? If so, why do we do it?
48. Give an example of an overloaded method that’s built into the .Net Framework Class Library:
VIDEO: OOP: Constructors
49. Implementing a constructor for your class will help you avoid making what sort of error?
50. When does the constructor method run/execute?
51. When the Car class has only 1 constructor, that takes a single parameter, what sort of compiletime can occur? Why is this error good / useful?
52. What two things identify a method as being a constructor?
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53. How can you have one constructor call a different constructor? Give a brief snippet of C# code
that demonstrates this, and then provide a brief explanation (in English, in your own words)
about how this works:
VIDEO: Basic Array of Objects
(You can jump to the 1:30 mark & watch from there – the first minute is not useful  )
54. In your own words BRIEFLY outline what the new operator does when asked to create an array
of Demo objects. Make sure that you’re clear what value (if any) that gets placed into each
array slot.
55. What does the keyword null mean/represent in C#?
56. What is a simple, intuitive rule for remembering what default value will be filled into a new
array?
57. In the below snippet of C# code, what does line (1) do? What does line (3) do? Do you
really need both? How are they different?
Demo [] ds = new Demo( 5 );
Console.WriteLine( ds[ 0 ] );
ds[1] = new Demo();
(1)
(3)
58. How do you call the printBox() method on the object at array slot #1 in the array named ds?
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VIDEO: Null References Within An Array
59. What happens when you attempt to call the printBox() method on the third slot in the ds array
(ds[2]) ? Why does that happen?
60. What sort of exception will see in when you attempt to call the printBox() method on the third
slot in the ds array (ds[2]) ?
61. How can you check (using C# code) if an array slot is not null? Provide a short snippet of C#
code, and a brief, intuitive explanation of how it works:
62. How can you check (using C# code) if an array slot is null? Provide a short snippet of C# code,
and a brief, intuitive explanation of how it works: